Apparatus for treating oils



Oct. 11, 1938. A. ENASH .1

. APPARATUS FOR TREATING OILS Original Filed lay 22, 1935 2 Sheets-Sheet1 mumm- 4M- Qchll, 1938. I A. A 2,132,965

APPARATUS FOR TREATING OILS Original]. Filed' May 22, 1935 '2Sheets-Sheet 2 Patented Oct. 11, 1938 UNITED STATES- APPARATUS FORTREATING OILS Arthur E. Nash, Mount Airy, Philadelphia, Pa,

assignor to Alcorn Combustion Company, Philadelphia, Pa., a. corporationof Delaware Application May 22, 1935, Serial No. 22,776 Renewed March11, 1938 3 Claims. (Cl. 196-110) My invention relates to systems of andapparatus for treating oils, particularly mineral'and hydro-carbon oils,especially petroleum, including products or components thereof, forrefining,

distilling or otherwise treating theoils, more particularly for crackingor converting the higher boiling into lower boiling oils, as in themanufacture of gasolines or other products.

It is the object of my invention to provide for stills or systems forcracking or otherwise heat treating petroleum (which term is hereemployed in the generic sense to include petroleum and other mineral andhydro-carbon oils, and components or products thereof) tube systemswhich,

particularly for large throughputs, shall, without material or anyincrease in size or internal diameter of the tubes, avoid excessivepressure drop between the inlet to and outlet from the heating system;in which heat shall be applied 2 to the tubes for the several streams ineach bank or zone substantially equally and at maximum rates; in whichthe number of tubesor total tube lengthshall be small for thethroughputs and heat inputs involved; and whichwithal shall bestructurally simple, and low in cost of construction and upkeep.

vTo these ends, and in accordance with my invention, the petroleum ispassed, through one or more heating zones of the heating system in aplurality of parallel streams which are entirely independent of eachother between their inlets and outlets to and from such zone or zones,in tubes disposed in a single row or tier in which the tubes for thedifferent streams alternate with each other, so insuring in each zone ortube'bank substantially identical heating effects upon the petroleum inthe several streams.

- Further in accordance with my invention, the tubes for each stream ofpetroleum are, to permit the tubes for the different streams to bedisposed in a single row, at their ends on the exterior of the furnaceprovided with fittings including tubular bends or connections offsetwith respect to tubes for the other stream or streams;

43 and further in accordance with my invention the fittings for eachpair of neighboring tubes of each stream are locked to'each other eitherimmediately, or through or to a fitting of an intervenin'g tube ofanother of the strear'ns. V no In connection with broader aspects of thepresent invention, reference may be had to copending applications,Serial No. 164,682, filed January 31, 192 7, of Nash and Alcorn for Heattransfer system; Serial No. 497,553, filed November 22, 5.5 1930, ofFrank H. Praeger, for Heat transfer system; and to Serial No. 721,480,filed April 20, 1934, of Nash and Shelly, for Heat transfer system. I donot herein claim subject matter disclosed or claimed in'aforesaidapplications, respectively owned by the same assignee as the presentinvention.

My" invention resides in the methods, apparatus, and structuralarrangements hereinafter described.

For an understanding of my methods and ap- 10 paratus, reference is tobe-had to the accompanying drawings, in which:

Figure 1 is a vertical sectional view, partly in elevation, of a furnacesystem for practicing my method and embodying one form of my appa- 15ratus;

Figs. 1a and 1b are explanatory diagrams;

Fig. 2 is a diagrammatic illustration of a twostream system inaccordance with my invention;

Fig. 3 is an end elevational view of tube con- 20 nections;

Fig. 4 is a plan view of a portion of the structure of Fig. 3 comprisingthe fittings of and connection between the neighboring tubes for v onestream; 25

. Fig. 5 is an end elevational view of theoffset tubular connectormember of Figs. 3 and 4;

Fig. 6 is a fragmentary sectional view, on the line B-6 of Fig. 3; I

Fig. '7 is an end elevational view of a modifie 30 form of tubeconnections;

Fig. 8 is aplan view of a portion of the structure shown in Fig. 7;

Fig. 9 is an end elevational view of a portion of the structure of Figs.7 and 8; 5

Fig. 10 is an-end elevational view, partly in section, of a portion ofthe structure, of Figs.

7 and 8;

Fig. 11 is an end elevational view of a box or solid casting type oftube connecting fitting; 40

Fig. 12 is a plan view of the structure shown in Fig. 11.

Referring to Fig. 1, illustrating one form of my apparatus suitableforpracticing one of my methOds the furnace is of the double ended type,each end preferably provided with means ,for burning fuel, such as oilor gas in particular, or powdered solid fuel.

In the example illustrated there are provided the heating zones orchambers H and HI, disposed within end walls I, l, floors 2', 2, androof walls 3, 3, which' may be disposed horizontally or inany othersuitable relation, or as shown, inclined inwardly andforwardlytoward themidsection 4 of the roof wall structure which, as a whole, may besupported from the roof truss 5, ofstructural steel, supported bycolumns 61.

Between chambers Hand HI. is disposed a. third chamber H2, open at itstop and bounded at each side by a bridge wall comprising the walls 'Iand la spaced from each other and supported or held by the metal columns8 disposed in the interspace, and covered with refractory structures 9,9.

With each of the heating chambers H and HI is associated a plurality ofmuflles or combustionchambers M and MI disposed side by side inhorizontal array, and each provided with a fuel burner II) provided withvalve II for controlling as to each muflle or combustion chamber M andMI the rate of combustion or amount of fuel burned, for controlling theinput of heat into the furnace system.

In the muuies M, MI combustion may be substantially completed, in whichcase there are discharged into the chambers H and HI products ofcombustion; or the discharge from the rnuiiles when combustion thereinis not completed may be flames or burning mixtures of fuel and air; allfor brevity termed herein combustion gases.

These gases, as they issue from the mufiles and as they pass over andabove the floor tubes, are

incandescent or of such high temperature that they may be classed asradiant, causing, if de-' sired, the side walls and bridge walls tobecome incandescent or radiant, thereby radiantiy to heat any of thetube structure within radiant view thereof.

The petroleum charged into the system is delivered through pipe I2 tothe pump P, controllable as to speed or output, which forces it in twostreams at suitabie pressure through the pipe connections I3, I4,controlled respectively by valves I5, I6, to the groups of tubes T andTI, al in series with each other within each group. The one stream S,that passed through the group of tubes T, enters, as indicated by thearrows, the

' first tube T2 of the bank of tubes adjacent the.

floor 2 of charnber H.

The stream S passes in succession through alternate of the tubes T2which at opposite ends of the furnace, on the exterior thereof, areconnected tc each other by the tubular connectors C which, ashereinafter described, are ofiset connector bends, crossing over orjumping the intermediate tubes of the other stream.

The second stream SI similarly passes through the group of tubes TI inchamber H2 and thence, as indicated by the arrows, to the tube T3, thefirst at the left end of the floor tube bank in chamber H, and thencethrough the remainder of the tubes T3 of that bank alternating with theaforesaid tubes T2, and similarly, on the exterior of the furnace atopposite ends thereof cross-connected by their tube connectors CI.

The streams S and SI leaving the last tubes T2 and T3 at the left of thefloor bank in chamber H, traverse, respectively, the tubes T and T5 ofthe roof bank in chamber H, then tubes T6 and T1 of the roof bank inchamber HI, and finally the tubes T8 and T9 of the floor bank in chamberHI.

The two streams pass out of the furnace system through the outlet pipesI1 and I8, which may be controlled respectively by valves I9 and 20, forfurther treatment separately or as indicated combined into a singlestream passing through pipe 2|, for any suitable further step of therefinery process, such, for example, :as may be effected in a reactionchamber, soakage chamber, fractionating'systern, etc., to which the line2I may connect either directly er indirectly through one or more otherprocess'zones, as well understood in oil refining in general and in petroleum cracking in particular.

The temperature of the oil charged into the system, and the temperaturesof the two streams S and SI at their outlets from the system may beindicated or recorded by any suitable pyrometric apparatus, including,for example, thermocouple J at the inlet to the system and thermocouplesJ I and J2 adjacent the discharge ends of the streams. The rise intemperature of stream S is indicated or recorded by the differ-v ence inelectromotive forces produced by the thermocouples J and J I, and therise in temperature of stream SI by the difference between theelectro-motive-forces produced by the thermocoupies J and J2.

The floor tubes T2 and T3 in the chamber H and T8 and T9 in chamber HIare disposed beneath and outside of the current of combustion gasesdischarged by the muifies M and MI to the end that the floor tubes shallbe heated pre ponderantly, or substantially entirelyby radiationdirectly from the combustion gases and to some extent from radiantwalls, with application cf heat to the floor tubes by convection to arelatively unimportant extent. I

The roof tubes T4 and T5 in chamber H and T6 and T1 in chamber HI areheated by radiation from gases and walls, and, depending upon theirrelations to the currents of combustion gases, either substantially orinsubstantially by convection.

The combustion gases in traversing the heating zones H and HI passinwardly and upwardly therein, over the tops ofthe bridge walls, andthence downwardly in a common gas current through the chamber H2, thegases sweeping the tubes T and T! in contact therewith, so heating themby convection, and those tubes, except as Generally, and as indicated byFig. 1, the

charging stock is the same in both streams which are subjectedpreferably to substantially identical heat treatments in each zone andthroughout the system of furnace zones with consequent substantiallyidentical effects upon the oil in the different streams. Usually it isdesirable that the temperatures of the streams at their outlets from thefurnace system shall be equal, the several -streams having under suchcircumstances been raised in temperature to like extents above the inlettemperature as determinable by the aforesaid pyrometers. The rise intemperature of the oil in each stream is dependent upon the heat inputinto the furnace system, controllable by valves II or otherwise, and bythe rate of flow of the oil in the stream. With equal rates of fiow inthe several streams, other things being the same, their changes intemperature between inlet to and outlet from the system will be equal.Assuming the valves I9, 20 to be omitted, as they may be, the valves I5and I6 may be adjusted to procure equal rates of flow in the differentstreams, by setting them manually, or automatically under the control ofthe pyrometers for each stream. Or this adjustment to equality of therates of flow in the streams may be effected by the valves l9 and 20 ifvalves I and ii are omitted, as they may be. In any event the adjustmentof the rates of flow in the different streams may be Such that thetemperatures of the different streams at their outlets from the furnacesystem shall be equal, the indications of these temperatures serving asinformation for either manual or automatic adjustment of the valves. aregenerally to be held at predetermined magnitudes, for which purpose thevalves may be adjusted to procure rates of flow which will procure thatpredetermined outlet temperature for each stream. Equality in outlettemperatures of the different streams is determinable by setting of thevalves as aforesaid and the magnitude of the outlet temperature isdeterminable in addition by the control of heat input into the system.

When the total lengths of the tubes for the different streams are alike,and their bores have equal cross sections, the rates of flow in thedifferent streams will be substantially equal when the drops in pressurebetween the inlets and outlets are equal.

When, as aforesaid, the total lengths of the tubes and their internaldiameters for the different streams are the same, with the same inletpressure the rates of flow in the different streams will be the samewithout need for either valves l5, IE or I9, 20, variation in speed ofthe pump P then sufiicing to determine the rate of flow in each streamsuch that the temperatures of the streams at their outlets shall beequal.

Particularly in cracking petroleum the similar effects upon thedifferent streams of oil in the furnace system may consist in raisingoil to cracking temperature, the cracking then to take place in areaction chamber or elsewhere in the system, or may consist in partiallycracking the oil within the furnace system with completion in a reactionzone or other process step of the system, or may consist in effectingall of the cracking action within the furnace system. And

' for these purposes the oil may remain in liquid phase throughout theentire furnace system, or

Y may be in liquid phase through part of the system and in vapor phasein another portion thereof, or in vapor phase throughout the furnacesystem.

Each of the streams is, maintainable in the furnace system at suitablepressure above atmosphere, generally at high superatmospheric pressure,'independently of the rate of flow in the streams as by valves I9, 20suitably adjusted to procure the desired super-atmospheric pressure atthe outlet of the furnace system; the valves l5 and t6, if present,serving then mainly to determine the rates of flow in each stream. Or inthe absence of valves l5 and IS, the speed of pump conditions would notordinarily ,be desirable. Different rates of flow in the difierentstreams,

or ,a predetermined ratio of the rate of flow in one stream to that inthe other, generally may be procured by suitable adjustment of either ofthe valves l5 or I6, both of which may be provided,

The outlet temperatures of the streams but only one of which isnecessary for this purpose.

While in general valves IS, IS and I9, 20 may all be omitted,nevertheless their presence ailords greater freedom and variety ofcontrols.

When charging stocks of different ranges of boiling points or othercharacteristics are charged to the different streams in a furnaceexemplified by Fig. 1 as to tube arrangement, as when the tubes are in asingle row and the tubes of the different streams alternate with eachother, an arrangement exemplified by Fig. 2 may be employed.

In this case a pump P is provided for each of the streams S and SI whichagain shall be understood to be within a furnace heating system F, ofthe character aforesaid, exemplified by Fig. 1. The rate of flow ofstream S may be controlled by the valve i5 and the rate of flow ofstream SI may be controlled by the valve l6. Pressure controlling valvesIS and 20 may also be employed, principally to determine at whatsuperatmospheric pressure the oil in the several streams shall bemaintained while in the furnace F. The streams may, as indicated, becombined and delivered into a chamber R for effecting some other step inthe general process; for this purpose R may be a reaction chambenasoakage chamber, or the like. Where the pressure in chamber R is to becontrolled there may be provided for that purpose an outlet valve 22,which, in the absence of valves l9 and 20 may control the magnitude ofsuper-atmospheric pressure of the streams within the furnace F, or thevalves I9 and 20 may effect a lower pressure in the chamber R which may,nevertheless, be super-atmospheric to such degree as determined by valve22.

With different rates of flow of the different charging stocks in thedifferent streams, the exit temperatures may be substantially equal,though generally may or will be different. For determining thetemperature rise in the stream S there may be employed, as before,pyrometer or thermocouple J3 at the inlet and at the outlet; and forstream Si pyrometer J5 at the inlet and J6 at the outlet.

The arrangement of ,the tubes of a bank or zone all in a single row ortier is contrasted with the tube arrangements diagrammatically indicatedin Figs. 1a and lb, in which, either for a single stream or a pluralityof streams they are disposed in two tiers or rows.

In Fig. 1a the tubes in the upper row are staggered with respect to, ordisposed above the interspaces between, the tubes of the lower row. Insuch arrangement the tubes of the lower or back row, which is fartherfrom the source of heat than the upper or front row, receive less heatper square foot of heating surface than the tubes in the upper row.

In Fig. 1b the tubes inthe front or upper row are practically directlyabove the tubes of the lower or back row; and for a two-stream systemthe tubes are connected criss-cross as indicated. In this case the loweror back row does not -absorb more than approximately half the amount ofheat per square foot of heating surface absorbed by the tubes in theupper row.

As compared with the arrangements of Figs. 1a and 1b, disposition of thetubes in a single row provides a much greater or maximum application ofheat per unit area of heat absorbing surface, with'the result that, fora. given total heat input to a tube bank, the number of tubes or totaltube length, when arranged in a single row,

is less than in the caseof either Fig. 1a or Fig. 1b. So requiring for agiven heat input less tube material, there results from the single rowarrangement a saving in cost, which is of particular significance whenthe tubes are composed of alloy steels or other high cost materials. Inaddition, the pressure drop between the inlet and outlets of the singlerow structure is, for a given rate of fiow of petroleum; substantiallydecreased; or for the same pressure drop a greater throughput ispossible.

By employing instead of a single stream, through the same tube lengthwhich would involve prohibitive pressure differential between inlet andoutlet particularly in the case of very large throughputs, the divisionof the throughput into several parallel streams or flows avoidssubstantial or any increase in the pressure drop without recourse totubes of greater than usual size or internal diameter, and byalternating the tubes for the different streams in a singlerowsubstantially identical and maximum heat inputs to the separate streamsare procured, and the heat is, evenly applied to and throughout theseveral.

follows: Twenty muflles M and twenty mufiles Ml disposed side by side,for tube lengths of 40 feet, all tubes 5%. inches external and 4 inchesinternal diameter (steel alloy 4% to 6% chromium, 0.5% molybdenum and0.15% carbon maximum) neighboring tubes in all zones, except H2, spaced10 inches between centers, and somewhat closer spacing in zone H2;fifteen tubes for each stream,

thirty tubes total, in each of the rgof banks; and ten tubes for eachstream, twenty tubes total for each fioor tube bank.

By way of example, when the required throughput and the practical limitin tube diameter results in an equivalent cold oll velocity of or inexcess of say ten feet per second, recourse to multiple streams with thetubes therefor alternating and disposed in a single row is usually ofad-j vantage.

When the tubes are disposed as described in a single row and alternatingfor the different streams, the cross connection at the exterior of thefurnace from a' tube of one stream to the neighboring-tube of the samestream, while crossing over or jumping the intervening tube of anotherstream, fittings of the character generally exemplified by Figs. 3 to12, inclusive, are provided.

Referring to Figs. 3 to 6, inclusive, the ends .of neighboring tubes T2,of the floor bank in chamber H for example, are-rolled or otherwisesecured in fittings or housing members 23 between which is the fittingor housing member 23a (Fig. 6) in which is rolled or secured theintervening tube T3 of the other stream. From each fitting or housingmember projects a bracket 24 parallelto the tubes, provided with slots,closed'at their upper ends, for receiving the clamps 25 through whichextend the set screws 26 which thrust upon the lugs 21 of thetubularcross-connectors C or Cl, each tapered at its inner end asindicated at 28 to fit a correspondingly tapered surface in members 23.The pressure exerted by screws 26 form at the tapered ends 28 pressuretight connections between the tubes and the crossconnectors C or CI.

The cross-connector rises from its tapered end 28 in an offsetting arc29 of about (Fig. 5) and continues in the offset portion 30 to a likearcuate in-turning and descending portion terminating in the tapered end28 in the fitting of the next tube of the same stream. The offset por-,.tion 30 of the connector C passes around or crosses over the fitting ofthe intervening tube of the other stream, as indicated in Fig. 3. Theadjacent connector Cl is similarly offset and crosses over or jumps thefitting of the tube with which the connector C communicates.

To prevent the tubes from shifting in position when the bends orconnectors such as C. Cl are removed for cleaning them and the furnacetubes, any suitable locking means may be provided.

In the arrangement of Fig. 3, the tube housings or fittings 23 forneighboring tubes T2 of the same stream are locked, by locking structure3|, to the locked to each other indirectly through the intervening tubehousing.

To remove the bend or cross-connector C, the set screws 26 are loosened,clamps 25 removed and the connector C then disconnected at its-taperedends 28 from the fittings 23 of the neighboring tubes of one stream, sogiving access to them for cleaning, during which they are prevented fromshifting by virtue of the aforesaid locking structures.

In Figs. 7 to 10, inclusive, a generally similar offset tube connectingstructure is shown. In this case the tubular connector C is areuate inform, and offset, as more clearly shown in Fig. 9. In this arrangement,Figs. 8, 10, the tube fittings or housings of neighboring tubes of thesame stream are locked directly or immediately to each other bystructure comprising the plate 32 and upstanding rib 33, with lookingbolts 3| locking them at opposite ends to the tube housings or fittings23. v

A similar bend and locking mechanism connect the fittings of the nextadjacent tubes in the other stream, each oifset bend 'or cross-connectorC and Cl passing around or jumping the housing for the intervening tubeof the other stream.

' In Figs. 11 and 12 is shown an offset connector C-for neighboringtubes of the same stream, of the box or solid casting type having at theends the parts 23 in which the tubes are rolled or otherwise connected,and each provided with a screw threaded plug 34 removable for access tothe tubes for cleaning. Here again locking structure 35 looks thehousings for neighboring tubes of one stream to the housing of theintervening tube of the other stream, comparable to the arrangement ofFig. 3. The connector Cl serves for neighboring tubes of theotherstream, crossing over in oifset relation to the intervening tubeand housing of the stream traversing connector C.

What I claim is: v

1. A system for heating petroleum to cracking temperature comprising apair of separately fired heating chambers, adjustable burner-meansindividual thereto for producing in each chamber a current of hot gases,at least two banks of tubes disposed within each chamber in single rowson opposite sides of each said current of gases, means connectingalternate tubes of each of said banks in series for passage therethroughoi separate streams of petroleum, means connecting said banks of bothchambers for passage of said streams therethrough in succession,supply-means for introducing under super-atmospheric pressure separatestreams of petroleum to said connected banks of tubes, separate meanstor each stream for controlling the magnitudes of the pressures of saidstreams upon discharge from said banks of tubes, means for adjustingsaid burner-means to vary the rate of heat absorption by said banks oftubes, and means for each stream responsive to the temperature rise ofeach stream for determining the setting of said adjusting means, and ofsaid pressure-controlling means.

2. A system for heating petroleum to cracking temperature comprising apairof heating cham bers in communication with each other, burner meansfor producing currents of combustion gases individual to said chambers,a' bank of tubes disposed adjacent the floor of each chamber, a bank ofroof tubes disposed adjacent the roof of each chamber, the tubes of eachbank disposed in a single row, connections for passage of the petroleumin different streams through alternate tubes of each row and insuccession through all of said tube-banks, inlet and outlet valves foreach of said streams for controlling respectively the rate of flow andthe discharge pressure of each of said streams, and means responsive tothe inlet and outlet temperatures of each stream for determining thesetting of said valves to produce a pre-'- determined temperature riseof each of said streams.

' 3. A system for heating petroleum to cracking temperature comprising adown-draft convection chamber, a bank of tubes therein, a pair ofheating chambers disposed, respectively,- on opposite sides of saidconvection chamber and in communication with each other, burner-meansfor producing currents of combustion gases individual to said chambers,a bank of tubes disposer. in a single row adjacent the roof of each ofsaid chambers, a bank of tubes disposed in a single row adjacent thefloor of each of said heating chambers and substantially below saidburner-means, connections between the tubes of said banks for passage ofpetroleum in two streams through said convection bank, through alternatetubes, of each row, oi. one bank of said floor tubes, of both banks ofsaid roof tubes, and of, said other bank of said floor tubes, in theorder named, inlet and outlet valves for each of said streams forcontrolling the rate of 'flow and the discharge pressure of each of.

' said streams, and means responsive to the temperature rise of eachstream for determining the setting of said valves to produce apredetermined temperature rise of each of said streams ARTHUR a. NASH.

